The present invention relates to combination locks, and more particularly, to a computerized combination lock that is fully self contained.
The technology of combination locks has changed very little over the past several decades. The basic design of such a lock includes a dial connected to a plurality of tumbler wheels for rotation. If the proper sequence of turning the dial is carried out by the operator, the gates in the tumbler wheels are aligned allowing the lever to drop in position for movement of the operating cam and bolt. Over the years, this type of lock has been improved several times and yet retains the same basic mechanism and function of the original combination locks.
A typical combination lock includes 50-75 machined parts of fairly close tolerance. The lock mechanism is thus relatively expensive, both in terms of material and labor to provide assembly and inspection. Furthermore, since the device is strictly mechanical, the parts are prone to wear and have a fairly high incidence of malfunction requiring repair by a locksmith. Also, with recent advances in listening devices and manipulators, these mechanical combination locks are now more subject to unauthorized opening. The mechanical structure of the lock inevitably provides metal-to-metal engagement sounds that can be recognized by the sophisticated listening devices that are available. Also, this traditional combination lock is susceptible to other types of electronic and visual surveillance to determine the combination.
Thus, it is apparent that a new type of combination lock is desirable to replace the traditional combination lock and overcome the shortcomings of the prior art. A combination lock that is electronic rather than mechanical, and that can provide the protection against unauthorized opening is believed to be the best approach.